1. Field of the Invention
The present invention relates to a photographing apparatus and an image processing method. In particular, the present invention relates to a photographing apparatus that uses eyeball movement information and reflects the eyeball movement information in a tomographic image of fundus, and an image processing method.
2. Description of the Related Art
In recent years, an Optical Coherence Tomography (OCT) apparatus capable of acquiring a tomographic image of fundus has attracted attention. One of the reasons for the attention is that an internal structure of fundus that cannot be observed by other apparatuses can be diagnosed in a non-invasive manner. Among others, a Fourier Domain-Optical Coherence Tomography (FD-OCT) apparatus capable of photographing at high speed and having a track record is the focus of attention on the market. The OCT apparatus is equipped with a fundus camera and Scanning Laser Ophthalmoscope (SLO) in the same apparatus and can acquire an OCT image of a desired area by displaying which area of fundus to be scanned by OCT.
On the other hand, higher quality of an OCT image is demanded to detect a micro tumor or abnormal conditions in terms of early diagnosis and early treatment. To achieve higher quality, an apparatus (Japanese Patent Application Laid-Open No. 2004-512125 (Patent Registration No. 3976678)) that causes an OCT beam to follow eyeball movement is disclosed.
Japanese Patent Application Laid-Open No. 2004-512125 adds a device to detect eyeball movement to the OCT apparatus. The device acquires an OCT image of a desired location by following an optic disk of fundus and controlling the OCT scanner in real time.
With the realization of speedup of the FD-OCT, the time needed to acquire an OCT image may be faster than the time needed to acquire eyeball movement information. Such an apparatus has a problem that position information corresponding to all OCT images is not necessarily obtained.
According to the configuration of Japanese Patent Application Laid-Open No. 2004-512125 described above, eyeball movement can be followed at high speed, but a tracking device needs to be added, leading to a larger apparatus in size and requiring expensive devices such as a scanner.
If images are superimposed in an OCT apparatus having a tracking device in which the acquisition rate of a tracking image is slower than the acquisition rate of an ordinary OCT image, an OCT image without position information is present also a problem of low precision of image superimposition due to micro saccade specific to the eyeball is caused.